Vehicle suspension



Jan. 28, 1947. A R. w. BROWN 2,415,026

VEHICLE SUSPENSION Filed July 23, 1943 5 Sheets-Sheet l h m 21 l 67 62 67 Jan. 28, 1947. w BROWN 2,415,026

VEHICLE SUSPENSiON Filed July 23, 1943 5 Sheets-Sheet 2 gvwowiom ROY \rV. fiIZOWN R; w. BROWN VEHICLE SUSPENSION Filed July 23, 1943 5 Sheets-Sheet 3 Jan. 28, 1947. w BROWN 2,415,026

VEHICLE SUSPENS ION Filed July 23, 1943 5 Sheets-Sheet 4 AIR COMPRESSOR IQOY W. BROWN whim 2 zrf Jan. 28, 1947. BR WN 2,415,026

VEHICLE SUSPENSION Filed .July 25, 1943 5 Sheets-Sheet 5 an my 225mg? tete n. 11

W t CLE SUQPENSION Roy W. Brown,

on, Ohio, assignor to The Firestone Tire & Rubber Company.

iihio, a coration of Ohio v Application July 23, 1943, Serial No. 495,947

This invention relates to a suspension for wheeled land vehicles such as gun carriages and the like of a type in which the carriage i adapted to be towed by some sort of draft vehicle for movingthe gun from place to place, and also is to be rendered immobile as when firing. More specifically, the invention relates to a pneumatic suspension which will serve as a cushioning means for the load and also, when it is desired to fire the gun, will become a Jack by means of which the carriage maybe lowered to the ground taking the load from the wheels and thereafter, may serve to raise the gun and carriage preparatory to moving to another location. By this means leaf or coil springs are eliminated and independent lowering and raising means for the carriage are not required. This invention is an improvement over the constructions of U. 8. Patent 2,103,6'70'and U. S. application Ser. No. 448,472 to R. W. Allen.

For illustrative purposes, the invention is depicted and described herein as it is applied to a mobile artillery unit, for which'the invention is of primary utility.

The chief objects of the invention are to provide in a gun inount an improved pneumatic vehicle suspension capable of functioning as a. jack to raise or lower the bed or frame of a vehicle; to provide a simple, light-weight, rugged wheel suspension of the character mentioned that enables substantial .wheel adjustment so that the vehicle bed may be supported at an adequate elevation for cross-country transportation; to provide a vehicle suspension enabling the vehicle to move at relatively high speed over rough terrain; and that enables mobile artillery equipped with the improved suspension quickly to get into firing position, and quickly to depart from said position, if necessary. Other objects will be manifest as the description proceeds.

Of the accompanying drawings:

Fig. 1' is a plan view of the bed or frame of the gun carriage shown in Fig. 2, the superstructure and gun being omitted; Fig. 2 is a front elevation of a Bofors" gun carriage in elevated or traveling position, and the improved pneumatic suspension operatively associated therewith;

Fig. 3 is a view of the structure shown in Fig. 2, in lowered or firing position;

Fig. 4 is a diametric section of one of the pneumatic suspension units of the vehicle, namely, the one at the left front wheel of the vehicle.

Fig. 5 is a detail sectional view, on a larger scale of a portion ofthe mechanism shown in Fig. 4, especially a braking device;

Fig. 6 is a plan view of th fluid pressure controlmeans of the vehicle suspension;

Fig. 'l isa transverse section thereof taken on line 1-1 of Fig. 6, the control handle being shown in elevation;

Fig. 8 is a section on the line 88 of Fig. 7;

Fig. 9 is a detail plan view, on a larger scale, of a cam plate constituting an element of the control device;

Fig. 10 is a side elevation of one of an'outer series of cams of the cam plate, as viewed from the line Ill-I0 of Fig. 9;

Fig. 11 is a section on the line iiil of Fig. 9 showing one of an inner series of cams on the cam plate; and

Fig. 12 is a transverse section, on a larger scale, through one of the valves incorporated in the control device.

Referring now to the drawings, especially Figs. 1 through 3 thereof, there is shown a gun carriage that comprises a main frame or bed 20 that extends longitudinally of the vehicle, and a top carriage, designated as a whole by the numeral 2|, that is supported by said main frame and movable relatively thereof in a horizontal plane, the top carriage being mounted upon a turntable 22, and provided with a gun 23 that is suitably swivelled for movement in a vertical plane, relatively of the carriage 2|. The top carriage 2| and mechanism carried thereby constitute no part of the present invention so thata description thereof in greater detailwill not be required.

The bed or frame 20 is tubular and horizontally disposed, and is substantially rectangular in cross section. At'the front and rear ends of saidmain frame are transversely disposed wheel-carrying assemblies generally designated 25 and;26 respectively, which assemblies will be described in detail hereinafter, said assemblies comprising wheels 21 which are provided with any known or preferred pneumatic tires for supporting the vehicle. The frame 20 is provided at a point intermediate the wheel-carrying assemblies with a transversely disposed arm 28 to which is pivoted, at the ends thereof, a pair of identical outrlggers 29, 29. The outriggers are arranged to be swung from an inoperative folded-back position as shown in full lines in Figs. 1 and 2 to the extended; operative position shown in full lines in Fig. 3, and in broken lines in Fig. 1. Each outrigger is provided at its outer end with a screw Jack 30 having a ground engaging foot plate 3| that is swivel-connected to the lower end of apost 32.

base plate 81' atta ned 3 Each post 32 is vertically adjustable by means of a manually operable crank 33, each of the latter being pivoted at 36 to enable folding into the position shown when not in use. Locking means indicated generally at 35, Fig. 1, is provided for retaining the outriggers in 'the'traveling position shown in full lines in said figure. Other screw jacks 30 are mounted at the front and rear ends respectively of is mounted upon the frame mem-- bers 20, 28 at the intersection thereof, and it is upon base plate bl that the turntable 22 is mounted.

The-wheel carrying assemblies 25, it at the opposite ends of the main frame 20 are of identical construction except for steering mechanism which is associated with the front wheels and which subsequently will be described. Each assembly comprises a forked arm 40 that has its forks pivotally connected to respective brackets, such as the bracket M, Fig.4, by means of hinge pins d2. Said brackets M are mounted upon the under side of main frame 20, at spaced points longitudinally thereof, the hinge pins 52 of the two brackets being in axial alignment. At the free, outer end of each forked arm til the latter is formed with a. bearing portion lit in which is journaled a pin id upon which is fixedly mounted an axial spindle 65, and joumaled upon said spindle is one of the wheels 27 of the vehicle. Each bracket iii is of dual construction and carries two hinge pins 52, one for each of the forked arms 40. The arrangement is such that each front wheel 2i may be swung or oscillated relatively of the main frame 20, the hinge pins 62 constituting the axes of oscillation of the wheels. By oscillating the arms 60 the wheels 2? may be tilted from the position shown in Fig. 2 to the position shown in Fig. .3 and vice versa. When the wheels are tilted to the position shown in Fig. 3, the gun carriage is in its lowered, firing position.

' For oscillating the forked arms M) to tilt the wheels 21 as described, suitable fluid pressure operated means is provided, and to this end the bearing portion d3 at the outer end of each arm 60 is formed with a downwardly extending bifurthe main frame 20. A circular 2,208,537. issued July 1'6, 1940.

being secured to ig/s w mm m w that is thereto by screws, The bellows comprises an annular lower end plate 68 that is secured to the upper end portion of lower tubular member-d9. preferably by welding, the lower end of the bellows secured to end plate 56 by means of a clamping rin bl that is secured thereto by screws. The bellows 5t comprises a tubular well of rubber and fabric construction which may be stially identical with the air spring bellows shown. in my prior U. S. Patent No. Intermediate its ends the bellows M is circumferentially constricted at two spaced apart regions, and in said under pressure to the =elongate the same whereby the lower tubular constructed regions are restrictive externally applied girdle rings 58, be. The arrangement is such that the bellows constitutes three interconnected chambers, that are deformable in operation, at which. time the girdle rings float and oppose expansion of the constricted regions of the bellows.

For supporting the-bellows structure at its upper end, a bracket Bil is attached to upper plate 53 thereof, said bracket being pivotally connected at 8i to' an upright standard 32 that is bolted to the top side of main frame 20. The standard 82 v is of dual construction so as to serve as an upper anchor for two bellows structures as is clearly shown in Fig. l. Welded to the top of bellows plate iii is a tubular. inlet member iii; that communicates with the interior of the'bellows through a port 8d formed in said upper bellows plate. The outer end of member 63 has a. metal conduit the connected thereto. which conduit extends to a reservoir of fluid under pressure (not shown) or to a compression pump (not shown). The arrangement is such that the admission of air bellows 5% will distend and member 29 is projected obliquely downwardly and thewheel 2i! is maintained in the substantially upright traveling position shown in Fig. 4.

Positioned about the bellows M is a hollow metal guard or shield .61 adapted to protect the cated ear M, Fig. 4, that carries a pivot pin 38,

' the latter being disposed transversely of the pin 6t, and located below a line that connects the axis of the axle id with the axis of oscillation 62 of the wheel. Pivotally connected to the pivot pin 48 is the lower end of a tubular member 49 that constitutes an element of a fluid pressure operated unit, said lower end of member 49 .being closed or sealed.

Said fluid pressure operated unit, shown in detail in Figs. 4 and 5, constitutes a part of the pneumatic suspension system of the vehicle. The.

lower tubular member 49 thereof is partly telescoped with an upper tubular member 5i of space or passage between the walls thereof. and

also to offer frictional resistance to relative axial movement of the tubular members. Secured to the upper end of upper tubular member 5!, preferably by welding, is the annular upper end plate 53 of a bellows 54, the end portion of the bellows bellows from gun fire or other damaging impact.

The shield b"? is open at its lower end, the upper end thereof comprising an inturned flange that is bolted to bracket Ed and bellows top plate 63, whereby the shield is supported concentrically of the bellows. Below the shield 61 an annular bumper support 69- encircles the lower tubular member as, concentrically thereof, said bumper support'being formed with a plurality of radially extending arms til, i that are attached to the lower end portion of e shield 61, so as to sup-- port said bumper support. The latter has mounted thereon a plurality of resilient bumpers iii, 70 that project upwardly therefrom into the open end of the shield iii in position to engage the lower bellows plate 56 when the bellows is inhated and fully distended, and thereby to limit expansion of said bellows, and to limit the projected movement of the tubular member 48 carried by the lower end plate 56 of said bellows.

The bellows as constitutes resilient means for holding the wheel 21 in traveling position shown and for cushioning shocks imposed upon the wheel when traveling overrough ground. Upon occasion, however, it may be desirable to secure the wheel in fixed determinate position, such an occasion being when the bellows is punctured or otherwise disabled,-or upon failure of the pump or other means supplying the bellows with air. To' this end mechanical means is provided. for preventing movement of the lower tubular member 49 relatively of the upper tubular member 5|. Said means comprises a pair of brake shoes I2, 12 that are located within the upper tubular member 5| in the lower region thereof that isin telescoped'relation with lower tubular member 49. In the region of the brake shoes, tubular member 5! is slotted or apertured at diametrically opposite regJns I3. 13 to enable the respective brake shoes 12 to project therethrough, and the outwardly presented faces of the brake shoes are provided with facings of friction material 14, such as brake lining, so that the brakes may have adequate frictional contact with the inner surface of the lower tubular member 49. For supporting the brake shoes 12 and for moving them radially of the tubular members 49, 5t, respec tive pairs of toggles are provided, each toggle ,comprising a pair of toggle links 15, 16. The toggle links l5, 16 of each pairare pivotally connected to each other by a pin ll. the connected ends of each pair of links being disposed within a slot 18 in a brake block, the pin 11 also extending through the brake block and. serving to connect the same to the toggle. The lower links 19 of the two toggles are pivotally connected to each other by a pin 19 that extends through them and has its ends secured in op osite sides of the upper tubular member 5|.

isutilized to secure a slotted block 89 in the tubular member 5!, the end portions of togglelinks 719 being disposed within the slot in said block 89. The toggle links i5 have end portions overlapping each other in a slot in a block III,

and said links are pivotally connected to each other and to said block 31 by a Din 82 extending therethrough. The block 8! is disposed within the tubular member 9|. the arrangement being such that movement of the block axially of said tubular member will operate the toggles to project or retract the brake blocks 72. In Fig. 5 the brake blocks are shown in operative engagement with the lower tubular member 99. i

For so moving the toggle block 9i. said block is secured to the lower end of a tubular stem M that extends'upwardly in the tubular member ti and has its upper end secured to a non-rotatable nut 85 that is mounted in the upper end of said tubular member 9! and arranged to move axially of the latter. To prevent the escape of pressure fluid from the upper end of tubular member 5|, an annular flexible diaphra m 8B of rubber or similarmaterial has its inner circumference clamped to the nut 85 by clamp member 81, the peripheral region of the diaphragm being clamped between the upper end plate 93 of the bellows and the bracket St. The use of the diaphragm 8t assures a fluid-tight seal between the nut 99 and tubular member 5! without the use of gaskets, glands, or other complex constructions that produce friction and are subject to leakage. For eii'ecting axial movement of the nut 95, a screw M is threaded therethrough, said screw having an unthreaded portion that is journaled in the bracket Eli and secured against longitudinal movement relatively thereof, the upper end of said screw projecting above the said bracket and provided with a handle or knob 88 by which the screw is manually rotated, to effect operation of the brake structure described;

As previously stated, the bellows 5d holds the wheel 21 in traveling position and cushions shocks imposed thereon, and in its latter function it is assisted and supplemented by an arrangement of the tubular members 49, 5|

The pin 79 constitutes a fixed connection for the toggles. and also whereby air. may be compressed within the lower part of the tubular member 49. To this end said lower tubular member is apertured at 90, in the region thereof that is disposed within the bellows 54" below the packing 52. This enables air from the bellows to pass into the interior of the member 49. Located within the member 49, immediately below the brake shoes 12 previously described, is valve mechanism for automatically shutting ofi communication between the bellows 54 and the chamber in the lower end portion of member 49, to enable compression of the air within said chamber, said valve being arranged to operate automatically to efiect equalization of th pressures in the bellows and said chamber, after the rir has been compressed, to obviate reaction which would cause rebound of the vehicle.

As is best shown in Fig. 5, an annular collar or plug 92'is fixedly secured in the'lower end portion of the tubular member 5|, immediately below the brake-slots 13 therein, the upper end of said collar being. formed with an inwardly extending circumferential flange to which is secured an axially disposed upwardly extending bonnet 93 of inverted cup shape, and a downwardly extending axially disposed tubular sleeve 94. The closed, upper end of the bonnet 93 may abut the bottom of block 89 as shown. The upper end portion of sleeve 9t telescopes into the open lower portion ofbonn'et 93, and is formed interiorly with a circumferential flange or rib that has its upper and lower margins reversely beveled was to constitute valve seats 95, 96 respectively. Immediately above the valve seat 95 the wall of the bonnet 93 is formed with a plurality of apertures or ports 91, and immediately below the valve seat 96 the sleeve 96 is formed with a plurality of apertures or ports 98. The bonnet 93 and sleeve 9d constitute a housing for a piston type valve structure 99 that-is mounted therein and capable of sliding movement axially thereof. Said valve 99 is formed with a reduced medial or waist portion, but is of such size each. side thereof as to slidingly engage the walls of the bonnet and sleeve respectively above and below the flange that comprises the valve seats 95, 95. The enlarged, upper end portion of the valve structure carries a circumferential facing or valve element I90 of rubber or other suitable resilient material adapted for fluid-tight engagement with the upper valve seat 95 when the valve structure is in lowermost position, thereby closing the ports 91 and preventing flow of fluid from the upper tubular member 5i into the chamber in the lower end of lower tubular member 59. In like manner the lower enlarged portion of the valve structure carries a valve element mi of resilient material adapted for fluidtight engagement with the lower valve seat 96 when the valve structure is in uppermost position, thereby closing the ports 98 and preventing flow of fiuid from the chamber in tubular member 419 into the tubular member 9!. As is most clearly shown in Fig. 5, the valve is open to admit the passage of fluid only when it is in intermediate position, and then only momentarily as presently will be explained.

For-moving the valve structure axially to its alternative operative positions, said structure is formed with a downwardly projecting stem G03 upon the lower end of which is mounted a transverse arm IIM, the opposite end portions of which carry respective arcuate gaskets I95 that frictionally engage the inner surface of the lower V aeraoao ment between tubular members 49, After the valve is seated on either of the valve seats 95, fit continued relative movement of said tubular members causes the member 59 to slide relatively of the gaskets and. littleor no strain is placed on the valve. The valve structure 99 is formed with an axial bore I08 extending from end to end thereof so that operation of the valve will not be affected by the presence or absence of fluid in bonnet 93 between the upper end of the latter and the upper end of the valve structure. The lower end of the upper tubular member Iii extends to a point even with or slightly below the lower end of the valve stem I03, and the lower end portion of said member is slotted as at I01, I01 to enable the arm I05 and gaskets I95 to extend therethrough so that the latter may engage the tubular member 39. The arrangement is such that if, on occasion, the tubular' members should move to completely telescoped position, it would be the lower end of member El and not valve stem I03 that would "bottom against the closure at the lower end of member 59.

carried by the vehicle. The suspension units are deflated or evacuated to lower the vehicle to firing position. For concurrently inflating or defiatingthe several suspension units, from either source of fluid pressure, a single control-valve is provided, said valve being mounted upon the bed or frame 20 of the vehicle and designated as a Assuming, that the elements of each pneumatic suspension unit are in the operative positions shown in Fig. 4, and the vehicle is traveling over rough terrain, it will'be obvious thatthe suspension is in dynamic condition and that lower tubular member 49 will reciprocate with relation to fixedly positioned upper tubular member 5| and there will be some compression and expansion of the fluid within the bellows 56. As the tubular member 49 moves upwardly over tubular member 5|, it moves valve 99 upwardly so that valve element IIII engages valveseat 96 and thereby closes communication between the chamber in tubular element 49 below the valve, and the bellows above the same. Thus continued upward movement of the lower tubular member effects compression of the fluid within its chamber, thereby ofiering increasing resistance to such upward movement of said lower tubular member. As soon as the impelling force on the whole by the numeral H0; The control valve is shown in detail in Figs. 6 to 12 inclusive to which attention now is directed.

As shown in Figs. 7 and 8, said valve comprises a metal housing. I I2 including a bottom cover I I3 secured thereto in an airtight manner, there being a chamber II i interiorly of the housing.

Within said chamber the housing structure H2 is formed with a centrally positioned, axially apertured boss I I5 that constitutes a bearing for a shaft H6, there being a face cam II'I secured to the lower end of said shaft. The shaft I I6 extends upwardly through the housing and through an externally. threaded boss I I8 formed on the top thereof, said boss I It being recessed to receive a plurality of frusto-conical packing gaskets I I'll. A gland nut I20-is threaded onto the boss H8 and compresses the gaskets H9 into fluid-sealing relation with the shaft H6. The gland nut I20 is positioned within an aperture I'2I in the top plate of frame 20, with the housing H2 disposed below said top plate, there being an index plate I22 secured to the top of frame 20, which plate extends over said aperture I2l., The plate I22 is'apertured to enable the; shaft )I I6 to extend therethrough, and an operating handle I23 is mounted upon the upper end portion of said shaft. Any suitable latch means such as that shown may be provided for latching the handle in determinate position. As shown, four latching positions are provided, which positions are 24 degrees apart from each other. The arrangement is such that turning of the handle I23 will rotate the cam Ill and cause the same to execute its intended functions, which functions are accomplished with only 72 degrees of rotation lower tubular member is spent, its direction of movement reverses, with the immediate result that the valve $9 is moved downwardly. Before elements I00, IIJI are unseated, and the chamber in the tubular ,member 49 is in communication with the bellows through the agency of ports 91,

98, thus enabling the pressures on opposite sides of the valve to equalize.

Thus the expansiveforce of the compressed fluid in the unit largely the valve element I 00 engages valve seat 95, there is a brief interval during which both valve of the cam. The functions of the valve III! are to inflate the pneumatic suspension system by means of a pump, inflate the system from a towed reservoir, shut off the system from its source of fluid supply, and evacuate the fluid from the system. Suitable indicia on the index plate indicate the positions to which the handle is turned to perform the respective functions.

The chamber IM of the control valve Ilfl has two inlet ports through which pressure fluid is admitted to the chamber alternatively from the pump or fromthe reservoir on the towed vehicle. The chamber IHialso has four inlet-outlet ports through which pressure fluid is passed to or received from the respective suspension units of the vehicle, and a single outlet port for opening the chamber to the atmosphere to evacuate said imits. All of the seven ports mentioned have individual valves operatively associated therewith,

which valves are opened or closed by the cam III as presently will be explained. As shown in Fig. 8, the two inlet ports are designated I25, I28, the four inlet-outlet ports are each designated I21, and the outlet or exhaust port is designated I23. At its outer end the'inlet port I25 communicates with a pipe or conduit I30 that extends matic suspension thereof are inflated to uniform "determinate pressure, but are not in communicationwith the inflating means, which may be a reservoir of fluid under pressure carried by a towed vehicle, or may be a compressor to the reservoir on the tow vehicle. The outer end'of the port I28 communicates with a pipe or conduit liite'x'tendingto a pump or air compressor. Theports I27 at their outer ends communicate with respective pipes 66a 65b, We andttd' that extend to the bellows ofthe respecupper end portion housing I42 that the chamber H4 and the inner ends of the ports I--'-I28. and since said valves are identical with each other, a detail description of one will suf- -flce. Referring especially to Fig. 12 of the drawings, it will be seen that each valve is received in a socket formed in the top wall of the housing 2, each socket comprising abore I34 opening at its lower end into chamber H4, an internally threaded counterbore I35 at the upper end of bore I34, and a still larger counterbore I36 at the upper onto th top face of the housing. Mounted in the bore I34 and projecting into the chamber H4 is a valve that is designated as a whole by the numeral I37. said valve constituting a selfcontained unit known as a package valve. The of valve I3! is of enlarged diameter threads to enable it to be tom of counterbore I35, place by said threads.

threaded into the botand to be retained in Threaded into the upper end of counterbore I35 is a plug I38, the head of which is received in counterbore I36. A packing gasket I39 is confined in counterbore I36 beneath the head of plug I38. A port opens into counterbore I35 between the bottom of plug I38 and-the top of valve I31, which port is shown in Fig. 12 as inlet Port I25.

The package valve I31 comprises a body or is formed in its upper end portion with a relatively large axial bore I43, the bottom of which is countersunk or tapered at I44, and opens into an axial bore I of somewhat smaller diameter therebeneath. The bore I45 extends nearly to the bottom of the housing I42, where it terminates in a yet smaller bore I46 that extends to the lower end of said housing. The tapered or countersunk region I44 constitutes a valve seat for a valve element I41, the latter being mostly of smaller diameter than the bore I43, and formed with a downwardly extending stem I48 that extends axially through bore I45 in spaced relation to the wall thereof, and is slidably received in bore I46, the lower end of the valve stem projecting from the bottom of housing I42. The lower end portion of the housing I42 is formed with a plurality of arouate kerfs or slots I49 that are disposed in planes parallel to the axis of the valve and extend to the axial bore I45 therein, the arrangement being such as to admit pressure fluid to, or vent it from, the under side of valve element I41. Formed'on the top of valve element I" are three radially extending arms I50 that slidingly engage the wall of bore I43 to guide the valve element therein. The latter is yieldingly urged toward its seat I44 by a compression spring I5I that seats in a shallow recess I52 in the top of the valve element, and has its upper end seated in a similar recess I53 formed on the under side of a bridge-piece I54 that extends diametrically across the bore I43. The bridge-piece I54 has its end portions received in suitable apertures in opposite walls of the housing I42, and is square in section so as not to turn therein. The dimensions of the bridge-piece are such that it does not substantially impede the flow of pressure 5 the use of packin The feature of using individual package" valves in the control valve of the suspension system makes it possible quickly and easily to replace defective or leaky valves, and obviates g in the valves, which previously has been a source of leakage.

The seven individual valves I31 of the suspension control are designated A to G inclusive (see Fig. .8), of which valves A, B, C, and D con- 10 trol the passage of fluid to and from the respecend of .counterbore I35, and opening 5 valves A, B, C,

and is formed exteriorly with screw 2 0 valves A to D inclusive.

ill

' that inlet valves E and F fluid through the bore I43. The arrangement is tive bellows 54, valve E controls the fluid inlet from the towed reservoir, valve F controls the fluid inlet from the pump, and valve G controls the vent. port. As will be apparent from Fig. 8, and D are disposed equi-distant from the axis of the valve shaft II 6, and are apart from each other. Valves E, F, and G are equi-distant from the axis of shaft II6, but the distance is somewhat less than is the case with Valves E and F are disposed on diametrically opposite sides of shaft II6, valve G being disposed 90 from each of them.

As is best shown in Fig. 9, the top face of cam II! is formed at its periphery with four elevated cam surfaces designated I56, I51, I58, and I59 respectively, which cam surfaces are disposed 90 apart from each other and are each about 58 in overall length. Also formed on the top face of cam II I, but spaced radially inwardly of the cam elevations aforementioned, are elevated cam surfaces I60, IN, and I62 respectively, which cam surfaces are about 16 in overall length. The cam surfaces I 56 to I59 are adapted to engage the valve stems I48 of valves A to D respectively and the cam surfaces I60 to I62 are adapted to engage the valve stems of valves E, F, and G respectively. Fig. 9 shows the positions of the cam surfaces I60 to I62 with relation to each other and with relation to cam surfaces I 56 to I59. This figure also shows the positions of all the cam surfaces with relation to all the individual valves when the cam I I1 is in the angular position indicated by the setting of the handle I23 as shown in Fig. 6. In the latter the handle is set at Deflate position, and Fig. 9 shows that with the handle in this position the cams I56 to I59 are in engagement with the valve stem's of valves A to D respectively, to open said valves, cam I62 is holding valve G open to open exhaust port I28, and cams I60, I6I are disengaged so are closed. Thus the several bellows 54 are concurrently evacuated through said port I28, which condition eifects the tilting of the wheels 21 to firing position. When the handle I23 is turned 24 to the position designated "Use," all cams are disengaged from all valves, and the latter are closed. This condition obtains when the wheels of the vehicle are in upright traveling position, it being understood that at such time the several suspension units are fully inflated to determinate pressure. When the handle is set at Inflate tow position, cams I56 to I59 are engaged with valves A to D to open thesame, cam I60 is engaged with valve E to open it and admit pressure fluid to the control valve housing and thence to the suspension units, and cams I6I and I62 are disengaged so that valves F and G the handle is set at "Inflate pump position, cams I56 to I59 are engaged with valves A to D to open said valves, cams I60, I62 are disengaged so that valves Eand G are closed, and cam "Si is engaged with valve F to open the same to admit pressure fluid to the system from the pump.

are closed. When necessary to slide the From the foregoing it will be apparent that by the simple manipulation of the handle I23 the suspension system may be charged from either of two alternative sources, the suspension units may be shut off from their source of fluid supply, or said units may be evacuated in unison. It will further be observed that when the handie is in Use position, as it is when the vehicle is traveling, the puncturing of any bellows or deflation of a single suspension unit for any cause will not result in deflation of any of the other suspension units since at this time the valves A to D are closed and the units are not in communication with each other.

When the suspension units are inflated, the wheels 21 are in the upright traveling position shown in Figs. 2 and 4. When the suspension units are in deflated condition the wheels 21 are in the tilted firing position shown in Fig. 3, and the bed or frame the screw jacks 30 is necessary. The use of the forked arms 40 for carrying the wheels makes it possible to position the pivots B8, that connect the arms to the tubular members 49, well below the axle 45 and the pivot points 42 of said arms, with the result that the suspension units may be made of greater length and capacity than otherwise would be possible. Furthermore, the suspension units have greater mechanical advantage than they would have if connected to the upper side of arms 40 since in the latter case they would be disposed more nearly parallel to the'arms 40.

The vehicle is not self-propelled, but is arranged to be drawn by a suitable tractor (not shown) to which it is connected by a draught bar I65, the latter being pivotally connected to the front end of the vehicle. Steering of the vehicle is effected by a pair of steering rods I14, I14 that are operatively connected at one end to the draught bar I65 so as to be longitudinally moved thereby, and at their opposite ends are connected to respective short bracket arms IBI, Fig. 1, that are mounted upon and project forwardly from respective discs or plates I82 that are secured to the respective axle spindles 45 at the front end of the vehicle.

In the event it is not convenient to inflate the several units, or any of them, from the reservo ir or other source of compressed air on the towing vehicle, a hand pump is provided. This hand pump is preferably installed inside the outrigger at the right side of the chassis. It may, however, be carried at any other desired position which offers space and reasonable protection 1 or such mechanism.

This auxiliary source of air pressure consists of .any of the usual types of air pump and is operated by a lover. The unit is protected against dirt and water and is covered by a removable plate at the topof the outrigger. To bring this auxiliary pressure means into action, it is only cover plate to one side, insert the operating lever in active position and connect the air line or nose to the inlet port at the valve housing. Of course, this hand pump is for use in emergencies and when power or some other quicker means of inflation is not present.

If desired, the valve connections may be so arranged that a single bellows or spring unit may be individually inflated. It is also contemplated to provide separate valve means at each unit for isolating or closing off that unit from others. In the event one of the bellows or other parts of a of the vehicle is so much nearer the ground that but little adjustment of particular suspension unit is damaged, it may be isolated from the main valve system and thereby inflation of the remaining units is accomplished without being affected by the condition of the damaged unit.

From the foregoing description it will be apparent that-the invention accomplishes the dual purpose of cushioning the vehicle while traveling, and of quickly lowering the frame of the vehicle to firing position when desired. The invention also makes possible higher speed of travel, it assures that the vehicle will follow in the path of its towing'tractor, and achieves the other advantages set out in the foregoing statement of objects.

Modification may be resorted to without departing from the spirit of the invention, or the scope thereof as defined by the appended claims.

What is claimed is:

1. In a suspension for a wheeled land vehicle. the combination of a vehicle frame, an arm pivotally mounted on the frame and projecting laterally thereof, said arm having an axle on the free end thereof on which axle a wheel is mounted, a fluid pressure operated unit pivotally connected at one end to the frame and at its other end to said arm near the free end thereof adapted to oscillate said arm, said unit comprising relatively moving elements, and brake means operatively associated with said relatively movable elements for holding the same fixedly in determinate relative position, upon occasion, such as upon failure of the fluid pressure.

2. A combination as defined in claim 1 wherein the relatively moving elements comprise a pair of tubes of which one tube is telescoped within the other tube.

3. In a suspension for a wheeled land vehicle, the combination of a vehicle frame, a plurality of arms pivotally mounted thereon and projecting laterally to opposite sides thereof, each arm having an axle on the free end thereof on which axle a wheel is mounted, respective fluid pressure operated units each connected at one end to the frame and at the otherv end to an arm near the free end thereof for oscillating the same, each of said units comprising relatively movable elements, means for concurrently charging and discharging said fluid pressure operated units, and mechanical means operatively associated with the relatively movable elements of each unit for holding the relatively movable elements of the unit fixedly in determinate relative position, upon occasion, such as the failure of fluid pressure in the unit. 4. In a uspension for a wheeled land vehicle, the combi ation of a vehicle frame, an arm pivotally mounted on the frame and extending laterally therefrom, the free end of said arm carrying an axle on which a wheel is journaled, a. fluid pressure operated unit pivotally connected at one end to the fram and at its other end to said arm near the free end thereof, said unit comprising a pair of telescopically arranged tubes that move axially relatively of each other in the operation of the unit, brake means carried by the innermost of said tubes and engageable with the inner surfac of the outermost tube to prevent relative axial movement of the tubes. on occasion, and means accessible from the exterior of the device for manually operating said brake means.

5. A combination as defined in claim 4 wherein the brake means comprises a pair of brake shoes that extend through respective openings in oppo- 7. A combination as defined in claim 4 wherein site sides of the innermost tube. the means for operating the brake means is a 6. A combination as defined in claim 4 wherein stem that extends axially of the innermost tube, the brak means comprises a pair of brake shoes, including means for eflecting axial movement of and the brake operating means comprises a pair 5 the stem relatively of said innermost tube. of toggles for moving the brake shoes toward and away from each other. ROY W. BROWN. 

